Relative to waiting line models: a. What is meant by the terms single-channel system and multiple-channel system? If a crew offour workers operates as a team in servicing a customer, how many chan- nels does the system have? b. Contrast the terms service timeand service rate. Explain how one can convert from time to rate. Why is this important? c. Explain the terms calling population, infinite source, and finite source. d. How does the phrase first-come, first-served apply in waiting line? Which models described in the chapter assume this?